383/71Duster

I’m running eddy rpms on my 440. They have the angled plugs. With the TTI headers the #6 is the tightest but it’s doable with a spark plug socket and box end wrench. My plugs are a 5/8”. Been a long time since I’ve messed with a stock head but I do remember the plugs being a lot tighter to headers than the edelbrocks with angled plugs.